Acylation. Part XXXII. A comparison of the charge distributions in keten and in dimethylketen and a determination of the relative reactivity of these compounds towards m-chloroaniline

Abstract

The rate equation for the acylation in ether of m-chloroaniline by keten takes the same form as that found for dimethylketen, viz, Rate =(k₁[ArNH₂]+ k₂[ArNH₂]²)[R₂CCO]. For keten the values of k₁ and k₂ are ca. 6 and ca. 9-fold greater respectively than for dimethylketen. Calculations by use of the Hückel method suggest that the main effect on the charge density along the C–C–O skeleton of substitution of Me for H is to reduce the negative charge on the β-carbon atom. It is argued that these results provide further support for the mechanisms of acylation by ketens which we have previously suggested. Our experiments render untenable Svetkin's generalisations about keten aminolyses.